, 


OCL(   -   ?"*- 


CONFIDENTIAL 

FOR  OFFICIAL  USE  ONLY 


TO  BE  TAKEN  INTO  FRONT  LINE  TRENCHES 

USE  OF  MINES 
IN  TRENCH  WARFARE 

(From  the  French  School  of  St.  Cyr) 


TRANSLATED  AND  EDITED  AT  THE 
ARMY  WAR  COLLEGE 


JULY,  1917 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1917 


WAR  DEPARTMENT. 

Document  No.  635. 
Office  of  The  Adjutant  General. 


WAR  DEPARTMENT, 

WASHINGTON,  July  23,  19 11. 

The  following  notes  on  Use  of  Mines  in  Trench  Warfare  are 
published  for  the  information  of  all  concerned. 
[062.1,  A.  G.  0.] 

BY  OBDEE  OF  THE  SECRETABY  OF  WAS  I 

TASKER  H.  BLISS, 

Major  General,  Acting  Chief  of  Staff, 
OFFICIAL  : 

H.  P.  MCCAIN, 

The  Adjutant  General. 


WAR  DEPARTMENT, 
THE  ADJUTANT  GENERAL'S  OFFICE, 

Washington,  June  19,  1917. 
To  all  officers  of  the  Army: 

You  are  advised  that  this  and  all  subsequent  documents  of  a 
similar  character  which  may  be  furnished  to  you  from  this 
office  are  to  be  regarded  as  strictly  confidential.  They  are  to  be 
kept  at  all  times  in  your  personal  possession,  and  are  not  to  be 
copied,  nor  are  any  parts  of  their  contents  to  be  communicated 
either  directly  or  indirectly  to  the  press,  nor  to  any  person  not 
in  the  military  or  naval  service  of  the  United  States.  In 
Europe  these  documents  are  not  to  be  carried  into  the  front-line 
trenches,  nor  farther  to  the  front  than  the  usual  post  of  the 
officers  to  whom  issued. 

Strict  compliance  with  this  injunction  is  enjoined  upon  every 
officer  into  whose  hands  any  of  these  confidential  documents 
may  come. 

BY  ORDER  OF  THE  SECRETARY  OF  WAR  ; 

H.  P.  MCCAIN, 

The  Adjutant  General. 
(3) 


CONTENTS. 


Page. 

Use  of  mines 5 

Specially  menaced  points 5 

Surface  observations 5 

Indications  revealing  enemy  galleries 6 

Listening  for  underground  noise 6 

Position  of  listening  posts 6 

Hours  and  precautions 7 

What  is  heard 7 

Distance  at  which  noise  can  be  heard 7 

Direction  from  which  noise  comes 8 

Useful  information  on  mines 8 

Defensive  systems 8 

Interval  between  galleries 8 

Start,  depth,  and  progress  of  work 9 

Barrage  trench  for  miners 9 

Camouflet 9 

Offensive  galleries 10 

Superimposed  galleries 10 

Mine  chamber 11 

Launching  an  attack 11 

Craters 11 

Craters  to  be  occupied 11 

Craters  that  the  enemy  occupies 12 

Craters  not  occupied 12 

Diagrams 9, 10, 12, 13 

4387  °— 1 7  4 


USE  OF  MINES  IN  TRENCH  WARFARE. 

[From  the  French  St.  Cyr  School.] 

(Secret   and   Confidential.      For  Official   Use   Only.     Not  to  be   Taken  into 
First-Line  Trenches.) 


USE  OF  MINES. 

In  sectors  where  the  distance  between  the  two  lines  is  below 
150  meters,  mine  warfare  must  be  used.  When  the  trenches  are 
farther  apart,  underground  warfare  is  seldom  employed.  In 
special  cases,  however,  when  there  are  strong  ventilators  and  the 
line  is  stable  enough  to  permit  of  it,  advance  may  be  made 
underground. 

SPECIALLY  MENACED  POINTS. 

The  most  vulnerable  points  evidently  are  the  following- :  The 
outposts  in  advance  of  the  line,  machine-gun  positions  approxi- 
mately located  by  the  enemy,  and  the  junction  points  of  the 
communicating  trenches  with  the  first  line. 

SURFACE  OBSERVATION. 

Underground  activity,  either  offensive  or  defensive,  is  first 
observed  from  those  points  in  our  lines  nearest  to  it.  All 
enemy  trenches  facing  a  salient  of  our  lines  will  be  the  object 
of  particular  attention  and  closest  daily  observation.  This  obser- 
vation of  the  first-line  trenches  should  disclose  the  presence  of 
enemy  underground  works  and  their  approximate  location. 

One  of  the  difficult  questions  in  mining  is  the  removal  of  the 
earth.  Expert  miners  sometimes  remove  the  earth  as  far  as  100 
to  200  meters  from  the  entrance  to  the  gallery.  They  throw  it 
on  old  ruined  shelters,  in  shell  holes,  on  the  reverse  of  the 
trenches.  But  these  precautions  are  not  always  rigidly  observed. 
When  the  noncommissioned  officer  is  absent,  or  the  enemy  bom- 
bards a  little  strongly,  some  one  in  the  working  party  not  want- 
ing to  work  overtime  throws  several  clods  of  earth  on  the 

parapet. 

(5) 


INDICATIONS   REVEALING   THE  ENEMY    GALLERIES. 

Freshly  placed  earth  coming  from  underground  is  white  and 
less  dull  in  color  than  that  of  the  parapets,  which  have  been 
washed  by  the  rain  and  blackened  by  explosives.  The  differ- 
ence in  color  for  the  first  day  or  so  is  striking.  In  chalk,  large 
white  spots  are  seen  on  the  reverse  of  the  German  trench,  daily 
growing  larger.  Without  doubt  they  are  working  near  by,  and 
should  be  watched. 

A  communication  trench  comes  out  at  a  salient,  and  runs  back 
from  150  to  200  meters.  Patches  of  chalk,  freshly  moved  and 
increasing  daily,  are  observed.  These  are  indications  of  un- 
derground work  starting  from  the  salient. 

Four  or  five  meters  of  enemy  trench  without  loopholes,  but 
with  loopholes  close  together  to  the  left  and  right,  may  mark  a 
gallery  entrance. 

A  miner's  working  relief  reaches  the  gallery,  each  man  carry- 
ing a  piece  of  the  frame  or  a  lining  plank  over  his  shoulder,  the 
ends  of  which  can  be  seen  over  the  parapet  or  through  the 
loopholes.  These  are  indications  of  a  gallery  position,  espe- 
cially if  the  men  all  move  in  the  same  direction  and  are  lost  to 
view  at  the  same  place. 

From  a  raised  point  on  the  second  or  third  line  we  see,  with 
field  glasses,  an  abnormal  accumulation  of  sandbags  in  a  well- 
known  area.  These  sacks  may  indicate  an  underground  gal- 
lery. 

Patrols  sent  out  in  front  of  the  enemy  trenches  sometimes 
bring  back  valuable  information.  They  may  hear  the  rumble 
of  ventilators,  the  noise  of  a  truck  moving  on  the  rails,  men 
working  near  a  gallery  entrance,  etc. 

The  enemy  fire  with  heavy  calibers  on  portions  of  the  first 
line.  Often  the  same  corner  is  bombarded.  This  may  indicate 
that  the  enemy  artillery  is  seeking  to  facilitate  the  miner's 
work  by  overthrowing  the  entrances  to  troublesome  galleries  in 
the  trench  attacked. 

Listening  for  underground  noise. — The  observation  of  hostile 
trenches  may  give  indications  which  will  limit  the  zone  necessary 
to  be  watched  ;  but  for  accurate  results  we  must  listen  for  under- 
ground noises. 

Positions  of  listening  posts. — The  listening  post  is  placed  at 
the  head  of  a  gallery,  in  an  angle  of  a  gallery,  in  a  deep  dug- 
out, in  a  niche  under  the  parapet,  or  on  the  bottom  of  the 


trench.  The  points  nearest  to  the  enemy  trench  are  selected 
for  the  listening  posts.  Below  the  outposts  there  is  always  a 
niche,  allowing  a  man  to  place  his  ear  to  the.  ground  (hence  the 
name  listening  posts). 

Hours  and  precautions. — The  most  favorable  hours  are  morn- 
ing about  4  or  5  o'clock,  at  2  p.  m.,  and  at  midnight.  All  the 
occupants  of  that  part  of  the  trench  must  keep  still,  and  all 
work  in  the  trench  and  the  mine  must  cease  for  a  given  time. 

What  is  heard. — The  inexperienced  ear  hears  too  many  things, 
and  is  easily  mistaken  in  the  noises  heard.  A  relief  passing  in 
the  enemy  trench  or  in  his  own  trench  at  40  meters  sounds 
strangely  like  the  noise  of  a  pick.  A  man  hitting  a  ground  sill 
or  striking  it  with  his  heel  gives  the.  idea  that  work  is  being 
done.  The  impact  of  bullets  on  the  parapet  at  night,  when  a 
fusillade  is  uninterrupted,  also  gives  the  idea  of  underground 
work.  A  man  filing  a  fuse  at  the  foot  of  his  loophole  suggests 
the  presence,  of  an  enemy  revolving  borer.  A  man  who  snores 
beside  the  gallery  entrance  imitates  the  noise  of  a  ventilator 
and  may  be  mistaken  for  it. 

However,  to  even  a  partially  trained  ear  the  noise  of  the 
pickax  is  characteristic.  It  is  not  a  harsh  sound,  like  that  of  a 
heel  striking  on  chalk  ground,  nor  is  it  like  the  shock  of  bul- 
lets piercing  the  parapet.  It  is  a  low,  rhythmic  sound,  with 
regular  cadence.  In  a  gallery  the  miner  works  kneeling.  When 
he  has  struck  five  or  six  blows  with  the  pickax,  he  takes  a 
breath.  He  repeats  this  process  about  12  times.  He  stops  two 
or  three  minutes,  and  the  second  miner  clears  away  the  earth 
and  fills  the  truck  with  sacks.  The  first  miner  resumes  his 
work.  It  is  easy  to  distinguish  this  regular  cadence  peculiar  to 
the  miner. 

In  an  infantry  company  there  are  always  several  miners  by 
occupation,  or  several  men  familiar  with  engineering.  These 
men  are  selected  specially  for  the  listening  service.  They  can 
give  accurate  information  to  the  officers  and  noncommissioned 
officers  of  a  sapper  company.  It  is  also  a  good  thing  for  a 
platoon  commander  to  descend  into  a  gallery  and  train  his  ear 
by  exchanging  pickax  signals  with  the  miner  in  the  adjoining 
gallery. 

Distance  at  ^vhich  noise  can  ~be  heard. — The  following  indi- 
cations help  in  determining  the  distance  of  underground  work : 

Four  men  work  in  a  gallery.  They  start  the  work,  then 
stop.  The  ear  is  placed  against  the  side  of  the  wall,  the  other 


8 

ear  being  covered  by  the  hand.  If  the  work  is  heard  under  these 
conditions,  it  is  at  a  distance  of  25  to  30  meters. 

If  all  noise  is  avoided,  and  the  work  is  heard  without  placing 
the  ear  against  the  wall,  the  distance  is  12  to  15  meters. 

If  there  is  talking  or  working  going  on,  and  still  the  under- 
ground work  is  heard  in  spite  of  it,  the  distance  is  8  to  10  meters. 

At  six  meters  a  man  can  hear  all  the  sounds  of  the  pickax,  the 
chalk  crumbling,  the  pieces  rolling  down  on  one  another,  the 
sliding  and  stacking  of  cases.  These  noises  sound  as  if  they 
were  immediately  below. 

At  four  meters  a  man  can  hear  talking,  the  scraping  of  but- 
tons against  the  wall,  the  miner  turning  around. 

The  humming  of  a  ventilator  can  be  heard  at  40  meters  with- 
out taking  precautions  to  hear  it. 

An  automatic  borer  can  be  heard  all  through  the  sector. 

Directions  from  ichich  noise  comes. — It  is  easier  to  deter- 
mine the  direction  of  noise  than  the  distance.  There  is  always 
a  chance  of  making  observations  in  the  galleries — one  on  the 
right,  the  other  on  the  left  of  the  noise.  The  exact  location 
of  the  enemy  underground  work  can  be  determined  by  inter- 
sections. 

The  engineer  companies  have  an  apparatus  for  intensifying 
the  sound  (strong  microphones).  They  reinforce  the  sound 
when  the  apparatus  is  in  the  direction  of  the  source  of  the 
sound.  Their  greatest  defect  is  that  they  magnify  sound  too 
much  and  too  many  things  are  heard.  Why  hear  for  a  distance 
of  100  meters  when  the  enemy  trench  is  only  40  meters  away? 
Everything  is  heard  in  a  mine  gallery.  It  is  difficult  to  dis- 
tinguish among  the  many  noises  that  of  the  enemy  miner's  pick. 
The  ear  is  amply  sufficient. 

The  beginner  has  a  tendency  to  exaggerate  the  proximity  of 
sounds.  He  thinks  he  is  close  to  the  enemy  when  he  is  still 
at  a  distance,  and  he  takes  steps  to  catch  the  enemy  by  ex- 
ploding a  camouflet,  whose  only  effect  is  to  retard  his  own  work. 

USEFUL  INFORMATION  ON  MINES. 

Defensive  system. — Two  arrangements  can  be  adopted :  Fan- 
shaped  arrangement  (fig.  a)  or  arrangement  of  independent 
parallel  galleries  (fig.  b).  The  second  arrangement  is  prefer- 
able. 

Interval  between  galleries. — Arrangement  2  being  adopted,  cal- 
culate the  interval  between  two  neighboring  galleries  in  such 


9 

manner  as  to  prevent  the  enemy  working  underground.  At  the 
head  of  each  gallery  two  elbows  of  6  meters,  with  boring  cham- 
bers, are  made.  A  6-meter  boring  is  made  from  each  chamber. 
At  the  bottom  of  the  boring  a  camouflet  is  placed,  effective  for 
radius  of  6  meters  (not  more  heavily  charged  or  the  gallery 
will  be  demolished).  The  camouflet  of  the  neighboring  gallery 
forms  a  tangent  to  the  first.  The  interval  between  the  two 
galleries  can  not,  therefore,  be  greater  than  36  meters.  In 
practice  we  would  take  30  meters. 

Start,  depth,  and  progress  of  work. — Start  from  first  line. 
Start  at  4  meters,  with  a  slope  of  20  per  cent  to  30  per  cent 
down  to  a  depth  of  10  meters.  Then  horizontal.  Length  to 
gallery  and  return  without  ventilation  can  cover  30  meters. 


Barrage  trench  for  miners. — If  the  enemy  passes  in  spite  of 
everything,  the  explosion  should  at  least  have  been  foreseen. 
The  enemy's  attack  must  be  limited  or  stopped,  and  this  is 
always  possible  after  the  explosion  of  the  charge,  which  may 
explode  well  in  advance  of  our  lines  and  act  only  as  a  strong 
means  of  launching  his  attack.  The  barrage  trench  is  estab- 
lished at  from  40  to  50  meters  in  rear  of  the  salient  T  (fig.  2). 
In  front  of  the  parapet  T,  wire  entanglement  R,  and  two  ma- 
chine-gun positions  M  and  M2  are  placed.  When  the  enemy's 
explosion  is  near,  only  a  few  men  are  left  to  occupy  the  salient. 
The  German  explosion  does  not  bury  anyone,  and  when  the 
attack  is  launched  it  breaks  down  at  the  entanglement  R. 

Camouflet. — The  sector  commander  is  warned  when  the  de- 
fense is  about  to  explode  a  camouflet.  About  10  meters  on  each 
side  of  the  gallery  are  evacuated  as  a  precaution.  The  only  danger 


10 

is  in  having  several  sandbags  fall  on  the  sides  of  the  gallery 
entrance.  Warn  the  working  party  charged  with  the  relief,  in 
order  that  they  may  not  block  the  passage  of  men  in  the  first, 
line.  Do  not  fire  or  make  any  changes  in  that  part  of  the 
trench,  in  order  that  the  enemy  may  not  locate  the  position. 
Do  not  fire  rockets  before  a  given  time.  The  camouflet  some- 
times shakes  the  ground  and  dust  is  visible.  Nine  times  out  of 
ten  the  camouflet  is  used  at  night. 

When  the.  enemy  explodes  a  camouflet,  fire  a  quantity  of 
rockets  to  locate  the  positions.  Fire  grenades  and  throw  bombs 
at  the  presumable  position  of  the  gallery.  Send  several  men  in 
front  of  the  parapet  to  listen  to  what  is  going  on  in  the  enemy 
trench. 

Offensive  galleries. — These  are  intended  to  pass  under  the 
adversary's  defenses.  Depth. — Start  at  first  line  when  it  is  far 


enough  away  from  the  enemy.  Start  at  second  line,  or  at 
special  communication  trench  about  20  meters  in  the  rear  of 
the  first  line,  when  the  enemy  trench  is  too  near.  (See  preced- 
ing.) A  depth  of  15  to  18  meters  should  be  attained.  The 
work  is  done  as  in  ordinary  galleries. 

Superimposed  galleries. — This  procedure  gives  splendid  re- 
sults in  deceiving  the  enemy,  who  thinks  he  is  protecting  him- 
self. The  defensive  gallery  starts  at  the  first  line  and  the 
offensive  gallery  starts  in  rear  of  it.  Both  galleries  are  on  the 
same  vertical  plane,  the  second  being  more  advanced  in  the 
direction  of  the  enemy  than  the  first.  An  enemy  listener  easily 
confuses  one  with  the  other,  and  the  offensive  gallery  passes 
under  him.  (See  figure.)  Distances  D  and  D1  are  the  same. 
The  miner,  M,  confuses  the  two  sounds,  and  the  offensive 
gallery  passes  under  him. 


11 

Mine  chambers. — They  are  of  special  interest  to  the  Engineer 
Corps  from  a  technical  point  of  view.  The  best  hours  for 
exploding  them  are  4  a.  m.  and  7  p.  m.  When  an  attack  is 
launched  at  a  great  distance,  or  when  there  is  to  be  no  attack, 
the  explosion  is  preceded  by  several  minutes  of  noise  in  the 
trenches.  We  commence  firing  and  show  several  bayonets  over 
the  parapet.  The  enemy  believes  an  attack  is  coming,  comes 
out  of  his  shelter,  and  mans  his  trenches.  After  the  explosion 
we  fire  on  the  mine  crater  for  four  hours  with  artillery,  grenades, 
and  bombs.  This  fire  should  cover  all  the  area  exploded  by  the 
mine  chamber  and  should  prevent  any  help  to  the  wounded  or 
buried. 

Launching  an  attack  by  means  of  mining. — The  mine  is  an 
irresistible  means  of  launching  an  attack.  In  a  mined  sector 
the  best  troops  completely  lose  their  bearings  for  several  seconds 
after  an  explosion.  These  several  seconds  prevent  the  machine 
gun  from  firing,  and  the  assailant  gains  a  foothold  in  the  first 
line  and  often  in  the  second. 

A  mine  attack  should  be  prepared  in  the  following  manner : 

Several  days  beforehand  the  attacking  troops  are  sent  to  the 
rest  camp.  The  plan  of  the  junipiug-off  trenches,  the  trenches 
to  be  attacked,  the  ground  trace  of  the  crater,  and  the  zone  of 
the  searchlights  are  drawn  on  the  ground  with  chalk.  Each 
attacking  fraction  is  placed  in  position,  with  the  materiel  to  be 
carried.  Each  fraction's  line  of  advance  is  marked  out  in 
chalk,  as  well  as  the  section  of  the  enemy's  trench  to  be  occupied 
and  the  position  of  the  barrage.  Every  detail  is  studied  thor- 
oughly, and  the  exercise  repeated  a  dozen  times.  The  attack 
is  then  carried  out  as  planned. 

Craters. — The  question  of  the  occupation  of  craters  must  be 
decided  by  an  authority  higher  than  the  platoon  commander. 
In  certain  cases  it  is  well  to  occupy  them ;  in  others,  inadvisable-'. 
We  will  discuss  only  the  practical  work  to  be  done  in  each  case. 

Craters  to  be  occupied. — Crown  the  rim  on  the  enemy  side 
with  a  continuous  trench,  joined  to  the  lines  by  (at  least)  two 
communicating  trenches.  Run  out  galleries  in  three  directions, 
first  for  protection  and  later  for  use  in  the  attack.  Construct 
bombproofs  on  the  half  cone  on  the  enemy  side. 

A  crater  is  a  position  advantageous  for  the  construction  of 
auxiliary  defenses,  for  the  removal  of  earth  from  the  galleries, 
for  massing  troops  for  an  attack,  and  for  flanking  the  lines. 


12 

Craters  that  the  enemy  occupies. — They  should  be  hampered 
with  bombs  and  grenades.  We  should  head  off  the  enemy  by 
means  of  two  well-placed  mine  chambers,  which  are  always 
possible  to  fire  rapidly  when  the  scheme  of  defense  is  by  inde- 
pendent galleries. 

Craters  not  occupied. — It  is  well  to  see  what  goes  on  at  the 
bottom.  An  outpost  of  several  men  or  a  sentinel  may  be  posted 
for  this  purpose  in  a  communicating  trench  on  the  friendly  rim. 
Two  communicating  trenches  may  also  be  used  to  crown  the 
friendly  rim  with  a  trench  with  slight  counterslope.  The  out- 
posts place  a  dozen  loopholes  permitting  fire  on  the  bottom.  We 
may  also  fill  up  the  bottom  with  chevaux  de  frise  and  other 
auxiliary  obstacles  that  can  be  thrown  in.  If  the  craters  are 
in  the  way,  we  can  always  turn  them  by  mining.  (See  figures 
for  different  examples : ) 


ntx 

—  Ixample  of  Wine  Croters  — 

t    hr»t  line  trench 
t   Crater 

RppCom mvnicatinrf  trench 

T  Trench  crowning  rim  on  enemy  jidc 

tt'E'fltw^allenes 
1C  Wiretntanfement 


by  the  enemy  — 


C     Mine  Crater 

T     I*  line  trench 

G*  6«llery  destroyed  by  I 
&<?  Intact'  galleriei  allo 
t-f,  Which  fillvjienemy  c 


» to  be  placed 


13 


—  /hint  crater  not  to  be  occvfltd*— 

t  Jvmpinjf  off  trench 

T   Trench  crownind  friendly  rim 
UM.1  Loophole*  overlooking  the  bottom  and  enemy  rim 

Planking  avtomatk-rlflt 

lYlre  entanglement 


Create  »ne.leva»«<)  w"l  (»Jlti«n  for 
placing  r-Kh.w  Jvn>  orthro.mj  tamfc. 
.t  M.nd  M'  which  tnrt.de  the  prti»  t»f 
tfy  trench. 


Crater  for  f  tanking  p*rpose»t 


Fig      H  Pt«troyin^  a  rortior  of  e«my  trench  by  mtaro  or  rwo  m(n«  c«rter>. 
6  >'  Commvniustmj   Gtrman  trenches  cvt  off  bjr 
5  5'  Salient  vnder'*hicji  E.E  ore  exploded 


lnj  machine (Jvm  between  5*3'cwt  off  by  rim»  of  cra)»r». 


o 


A     000  550  1 53     1 


